Combined and individual effects of diatomaceous earth and methyl eugenol against stored products insect pests

The insecticidal activity of a proprietary diatomaceous earth, Detech, and methyl eugenol was tested with Sitophilus granarius (L., 1758), Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae), Rhyzopertha dominica (Fabricius, 1792) (Coleoptera: Bostrychidae), Tribolium confusum Jaquelin Du Val, 1868 (Coleoptera: Tenebrionidae) adults at Stored Products Pest Laboratory of Plant Protection Central Research Institute (Ankara, Turkey) in 2020. A range of doses of Detech (100, 250 and 500 mg kg(-1)) and methyl eugenol (5, 10 and 15 mg kg(-1)) were used. To determine insect mortality, at a range of times after treatment, and half-doses of both products were also studied in order to examine simultaneous use for synergistic effect. The greatest effect of Detech on R. dominica, S. zeamais, S. granarius and T. confusum was observed with 500 mg kg(-1) giving 81, 29, 26 and 18% mortality 28 d after treatment (DAT), respectively. Methyl eugenol at 15 mg kg(-1) gave complete mortality with R. dominica adults 3 DAT. Simultaneous application of both products did not give complete mortality in test insects. The data show that Detech and methyl eugenol are promising treatments for the control of insect pests of stored products.